1. Field of the Invention
This invention relates to improvements in an intake manifold in a V type multi-cylinder internal combustion engine, and more particularly to a branch runner arrangement in the intake manifold to improve productivity and maintenance effeciency of the engine.
2. Description of the Prior Art
In a V-type engine in which right and left side banks are arranged V-shaped in cross-section, usually an intake manifold is provided between the both banks while an exhaust manifold is provided outside of the banks as disclosed for example in Japanese Patent Provisional Publication No. 62-153516, which is illustrated in FIG. 6 of the drawings of this application.
In FIG. 6, an internal combustion engine includes right and light side banks 72, 73 having engine cylinders and arranged V-shaped in cross-section. The intake system of this engine includes a surge tank 74. The surge tank 74 is communicated through independent branch runners 75, 76 with the engine cylinders. The surge tank 74 is disposed above the left side bank 72 and is formed therein with two expansion chambers 77, 78 which are located one upon another. The lower expansion chamber 78 is connected with the right side bank 73 through the branch runners 75, while the upper expansion chamber 77 is connected with the left side bank 72 through the branch runners 76, thus making the intake manifold arrangement compact.
In the above intake manifold arrangement, the connecting end sections of the respective branch runners 76 to the upper expansion chamber 77 and the connecting end sections of the respective branch runners 75 to the lower expansion chamber 78 are located shifted to each other on an imaginary horizontal plane, corresponding to the locational relationship of the respective engine cylinders. Accordingly, the upper side of the left side bank 72 is unavoidably extensively covered with the respective branch runners 75, 76. This makes difficult the installation operation of ignition devices at the left side bank 72, thereby degrading productivity and maintenance effeciency of the engine.